Setup of Vtime and vmin for Linux under serial port programming

Vtime defines the amount of time that is required to wait (the value cannot be greater than cc_t).

Vmin defines the minimum number of bytes required to wait.

Options.c_cc[vtime] = X; Sets the time-out period from acquisition to 1 bytes to start a timer

Options.c_cc[vmin] = Y; Set the minimum number of bytes required to wait

Effects on the read () function in the original mode :

1, x=0,y!=0. The function read () returns only if the data of y bytes is read or when a signal is received;

2, x!=0,y=0. Even if no data can be read, the read () function waits for the X time amount to return;

3, x!=0,y!=0. The first byte of data to start, the first to meet the received Y bytes or up to the timeout time x any one condition, read () returns;

4, x=0,y=0. Even if no data is read, the function read returns immediately.

Example:

Through the serial port connection ID card reader, requires that the read serial port at least 6 bytes of data returned immediately, you can set the above two settings of the serial port as follows:

options.c_cc[vtime]=0;

options.c_cc[vmin]=6;

X = = 10 indicates a time-out of 1 seconds

Setup of Vtime and vmin for Linux under serial port programming